Hydrogen fuel cells are thought by many experts to be the way we'll power the cars of tomorrow. They're an efficient way of storing energy and are clean to boot — the only emissions they produce are water. If tomorrow's cars will be powered by fuel cells, we're going to need a lot of engineers today to help us get there. If the past decade has been the domain of the financial engineer, the next 10 years will be the era of the green engineer. Graduates of engineering schools who come out with focuses in fuel-cell technology will find themselves recruited and swooped up by companies like first-round picks in the NBA draft.